The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An aircraft is moved by several turbofan engines each housed in a nacelle also housing a set of related actuating devices connected to its operation and performing various functions when the turbofan engine is running or stopped. These related actuating devices in particular comprise a mechanical thrust reverser actuating system.
A nacelle generally has a tubular structure with a longitudinal axis comprising an air inlet upstream from the turbofan engine, a middle section designed to surround the fan of the turbofan engine, and a downstream section housing thrust reversal means and designed to surround the combustion chamber of the turbofan engine. The tubular structure generally ends with a jet nozzle whereof the output is situated downstream from the turbofan engine.
The nacelle also typically includes a top designed to receive a fastening pylon making it possible to fasten the nacelle and the turbofan engine to a wing of the aircraft.
The term “downstream” here refers to the direction corresponding to the direction of the cold air flow penetrating the turbofan engine. The term “upstream” designates the opposite direction.
Modern nacelles are designed to house a bypass turbofan engine capable of generating, by the rotating blades of the fan, a hot air flow (also called “primary flow”) coming from the combustion chamber of the turbofan engine, and a cold air flow (“secondary flow”) that circulates outside the turbofan engine through an annular passage, also called “tunnel.”
A turbofan engine typically includes a so-called “upstream” part, comprising the blades of the fan, and a so-called “downstream” part, housing the gas generator.
The downstream section of the nacelle for such an engine generally has an outer structure, called Outer Fixed Structure (OFS), and a concentric inner structure, called Inner Fixed Structure (IFS), surrounding the structure of the engine strictly speaking downstream from the fan. The inner and outer structures define a tunnel designed to channel the cold air flow that circulates outside the engine. The outer structure in some cases includes a thrust reverser comprising one or more cowls sliding along the longitudinal axis of the nacelle between the position allowing a reversed flow of air to escape and a position preventing such escape.
Such a thrust reverser makes it possible, owing to the reversed flow of air, to reduce the braking distance of the aircraft upon landing.
An airplane wing is also generally equipped with spoilers that make it possible to orient the aircraft. A spoiler is situated on the front face of the wing. When a spoiler is in the lowered position, it becomes very close to the nacelle, in particular at the fastening of the latter under the wing of the aircraft, only on the nacelle side.
This risks creating a physical interference, as well as an aerodynamic interference with the sliding cowl of the thrust reverser, when the latter slides toward the thrust reversal position.
One proposed solution to eliminate this interference is to make the upper part of the nacelle stationary, i.e., the top of the latter corresponding to the fastening area of the nacelle under the wing of the aircraft, while widening the inner fixed structure.
The aircraft being symmetrical, all of the nacelles mounted thereon experience this interference phenomenon, with the result that all of the nacelles have a stationary area with respect to the thrust reverser on either side of the top of the nacelle.
The stationary area of the nacelle therefore does not participate in the thrust reversal performance. In order to offset this drawback, it is necessary to increase the travel length of the thrust reverser.
Such a modification causes an increase in the mass of the nacelle and a decrease in the effectiveness of the counterthrust.
One aim of the present disclosure is therefore to provide a nacelle not having the aforementioned drawbacks.